@ Haley : If it's just one side and it's on the lip, it's most likely cystic acne. Try washing with Dial soap. See if it comes to a "head," but don't pop it because it could be a cyst and not just a pimple. Do you shave down there? Because sometimes you can get an ingrown hair or a cut from a razor can become infected. Reassure your mom you've never had sex. Tell her you're worried you injured it shaving or that you may have a Bartholian cyst (that's like a pimple on your vagina and has nothing to do with sex-- just hormones and stopped up glands/pores just like regular acne). You can also check with a doctor in private without her telling anyone. You're protected by HIPPA laws from her telling your mom, since you're over 18. Your regular GP can check you out. You don't even have to tell the nurses why you're coming in.

@ Jess : There are a few things that could be happening, which happened to me about your age: 1. You have some acne down there. Nothing to worry about. 12 year olds get pimples all the time. Use Dial soap. It's the only anti-bacterial that really worked for me. Clears up acne. Be gentle while washing. 2. You could have the female equivalent of athlete's foot. If you wore wet shorts or a bathing suit or even exercised/sweat in too-tight underwear, it's a mild fungus. Get some cream from the drugstore for vaginal itching and yeast infection. Has Nothing to do with being sexually active. OR 3. If those things don't work, you may have developed an allergy to your laundry detergent. Ask your mom to buy something without dyes and perfumes.